Xiaomi India — My redmi 2 prime-service centre has change the motherboard instead of 2 gb ram they set the 1 gb ram in my phone

I earnestly request you to solve my problem, i an facing too much of problem.

when i submited my mobile in service centre they told me that they will return my mobile after 2 day but they hvn't return till now.when i gone there and they gave my mobile and i have seen that they changed my motherboard.

consumer id- WXIN[protected]
plz resolve my problem as soon as possible