Obviously your supplier has problems in designing and assembling the air cooler as per the client specification. I would change the supplier in that case. As mentioned earlier, Hudson and GEA can definitely provide you with an integrated design. Probably there are others on the market as well.
If you are acting on the side of the engineering design company and you must follow the client specification which requires automatic control of blade pitch, you need to find a workable solution. Either you can do it together with the supplier who already replied with a negative quote (and working with them seems to be a problem because they apparently lack experience in this subject), or to change the supplier.
Designing for variable blade pitch is not a rocket science, but you need to understand that e.g. decrease of ambient temperature will put additional load on the fan motor with a blade pitch set at the maximum angle at a higher temperature. The fans will trip or the motor will burn when temperature decreases over night. So there must be a reliable instrumentation system that will measure all relevant parameters and adjust the blades accordingly. Not a rocket science as I sad, but I wouldn't put my trust into someone who has never done this thing before.