cannot open email in Comcast site. Cannot send emails

Comcast webmail will not load -all it says is try to refresh. IE or Mozilla. Rebooted their modem/router as per their instructions. Finally can get in (intermittently) but emails are not accessible on a regular basis. Get the "slow server" error and to cancel request constantly. Cannot move from one email to the next without getting it. Cannot send emails and it won't save to draft. Now no new emails are coming in from outside. Have been on chat twice, called and was escalated to 3rd level. She said to defrag my computer and other than clearing cache/cookies 3rd level support is clueless. I think it has to do with the supposed upgrade and new modem I received. 3rd level support said that might be it but didn't know. I never had this much problem with the old modem. So much for their "guarantee. It's easier to blame something on consumer computer or hardware vs. acknowledging issues with their servers or that they have not upgraded their programs. This is a service that we pay for and a lot of money- these issues should not be happening.