Bluestar AC service

We brought this AC around 1 year back, and we had to service it 2-3 times plus had filled gas 2 times. My father was directly reaching out the technician not involving the shop owner from where we brought or Bluestar support. The last time the technician filled gas the ac only worked fine for just few days. Then from right half cold air and left half was giving hot air. We called him as he said there 6 months guarantee if any thing happens but he never came to check back. I felt that my father got deceived by directly reaching out to technician. As the summers are approaching should this time we call the shop owner or Bluestar customer care for ac repair? How's your experience with Bluestar ac and its service provided? I don't know if we had any leaks in pipe, but I know for sure that we need to fill the gas again. What would the total cost be?