Dont trust Comcast upon renewal of contract

As I renewed my new contract with comcast I was told I would get a new modem as the one we have is old and "the new ones are much better"  The lady said she would set that up for me and that I would be contacted.  After a couple of months of no contact I call comcast.  I was told she did not put that in the work order and I would have to buy one.  I asked if the conversations were recorded and was told yes.  My obvious repsonse was let's pull that conversation and listen to it.  "oh, we cant do that".  I ask, who can I talk to about this?  Response. "nobody, the gal you worked with should have entered that"  Note: she is trying to sell me additional services of cable and internet while telling me too bad on your modem

Thank you comcast for promising and not delivering!!!