Acknowledgement not received for registered ad letter

Since travelling is very expensive and time consuming, a form was sent by registered post to Life Insurance company , Mumbai address
Registered ad was used, so that the sender could get an acknowledgement .
Though the letter was sent more than one month ago, the acknowledgement was not received
Additionally the online tracking shows that it is delivered to United Insurance instead of Life Insurance company.
Now the sender has to waste time enquiring at the post office.