CTDI is useless

I sent my Huawei P9 in to get my Microphone Port, Charging Port and Microphone problem fixed. CTDI have been trying to force me to replace my screen and back cover, even though a condition on their quotation clearly states "CTDI reserves the right to inform the customer of any additional work required that is discovered in the process of repairing the device as well as the resultant cost, if any. CTDI will only repair additional work if approved by the customer." which I do not accept. They refuse to fix the phone as they now state it won't pass their Quality Control. They are clearly violating their own condition on their quotation.