Hey.
I renewed my RTR about 2 months ago from WPC Kolkata and had the same problems like you. In my case I waited for a month before contacting them. When I did, I was told that the renewal was sent by post and should arrive any day. I waited again for a week before calling. This time I asked for the tracking number.
On tracking, it showed that the post had been sent when the WPC said they did. Only it didn't leave Kolkata and was at some sorting facility.
It arrived 3 weeks later. Total time taken from the date of me posting the application was 2 months. Sometimes it is WPC's fault, sometime it is the postal department. They send registered posts, not speed posts.