Airtel Landline Phone — package changed without any notice

Since we have started using the Connection , we have been using one package consistently but later suddenly realised that it is deactivated and we had been using the connection as per the previous package leading to the increased phone bills..........
When asked they say that that package is no more available so they cannot activate it .............
We have not told the company to change the package....... but it is done - dont know how...........
In the end we have increased phone bills