In the Name of Allah, The All Knowing, The Most Merciful.
Quranic verses regarding the question of asking for help from someone other than Allah
1st

{surah55:aayah5}
Here the Quran states that your real helpers and friends are Allah , his messengers and those believers, who establish regular prayer and give charity while they are bowing in prayers.
Both the shia and sunni schools of thought agree that this verse was revealed in the holy mosque of Prophet when Imam Ali gave his ring to a beggar in mosque during his prayer while bowing.
These are the refernces for the tafseer of this verse

2nd

{surah160:aayah7}
Prophet Musa as was once asked by his people for the water as there was a scarcity of water. He then supplicated to Allah and wastold to strike the rock with his staff. When he did so water gushed out forming 12 springs.
Questions arises that: If it wasn't good to demand help from anyone but Allah then why didn't the Prophet refused to help the people?, Was there a need of striking the rock? Allah could've helped them by a simple way like by a rainfall.
Why was all this done in this way?.
Indeed there was a message hidden in it by Allah to be conveyed.
Hence demanding help from the Prophets is not a bad tradition. The staff. There was nothing special in it.then How is it possible for a staff to deliver such a miracle? The answer isthat it is not the staff but it is its atttachment with the Prophet whichis the reason for its miracle because source of its power is none but Allah
Similarly the Tabarrukats which the Shia have respect for are ordinary but just like the staff of the Musa and due to its attachment and its bonding with such personalities they are Not ordinary.
3rd

{surah40:aayah27}
Prophet Sulaiman was given the authority over all kind of creatures. The small the big, the short the tall, those which live on land and those which live in water, those which fly in air and those which move through the soil. All of them were obedient to him.
As it is mentioned in Holy Quran thatProphet Sulaiman said to his own men that which one of you can bring me the throne of Bilqees before she arrives here. Said one from the jinns 'I will bring it before you rise from your seat'. Said one who had knowledge from the book ,'I will bring it to you within the twinkling of an eye' .
This person was the nephew of Prophet named Asif bin Barkhiya whom he had taught the knowledge. Some say he had the knowledge from the Holy Quran and that the knowledge he had of was just the 'Bismillah'. Although he was not a Prophet he was able to bring the throne in a time taken by an eye to twinkle and Allah knows how far it was.
Even though Sulaiman was theProphet of Allah , Why he sought help from his nephew ?. Was he not able to help himself ?. If taking help from someone other than Allah is not ok then Why did Prophet Sulaiman take help from his nephew ?
So if a person who had some of the knowledge from the Holy Quran can help a Prophet in such a way then definitely a Prophet has more ability and authority specially the PROPHET upon whom whole of the Quran was revealed. He can definitely help. Neither distance is a problem nor the time.
There is no doubt in the fact that Allah is the definite and true source of guidance, power and assistance and that such personalities are the bridges or mediums which help in connecting us to Him .
In the 1st verse Allah by Himself has appointed Imam Ali as the helper and it is the clear proof for the Imam Ali being Wali [helper/guardian] of the believers.
As per the 2nd and 3rd verses. It can be concluded here that there is no harm in seeking help from someone other than Allah - The Prophets and those whom He appoints [heirs].
The Prophets always select good when they select because they are appointed by the Allah . And can there be a doubt in His selection ? No Never.