5 weeks and rims still not repaired

I gave in my two rims to Wheel Collision for repairs in April. It was returned once half repaired. It was immediately sent back to them by Tiger Wheel and Tyre. Its now the fifth week and it is impossible to contact anyone because their phone is forever engaged. These are Mercedes AMG rims that still I have received no response for. Why such poor service? I will also be complaining to Mercedes about this as I have had to borrow a vehicle for 5 weeks. Why has Mercedes Benz approved a supplier like this that treats its clients so badly. It is disappointing that they will keep a rim for 5 weeks and not even consider repairing it properly. Where is my rims?