Audi A4 2008 TDI 2.0, door unlock problem

Hi All,

This is my first post on Audi forum. I have recently bought Audi A4. I am enjoying the ride. One thing I noticed in the car is driver side door doesnt unlock from the key fob. I have to unlock it with key.
Last week my front passenger door started to giving the similar issue.

Can any one tell me how much will it cost me to repair? (both doors). Is it worth to goto audi dealer or local garages will fix it with ease as well.
can anyone recommend good garages which can do this job economically? because audi dealers will charge so much
I have seen few posts where people repaired them by themselves, however I have never done anything like this in the past.

thanks in advance,

Zain