Problem with Avast account

I am thinking of upgrading my Avast account from the free trial to full membership, but am a little concerned to be have been told there is already a problem with it. I used to get alerts asking me to try the free trial while I was already on it, which rang alarm bells.
I rang the help desk, and an operative said she would check and ring back. When she did, she said there was a problem asked me to hand over control of my computer to fix it. I ought to have been convinced that this as genuine, as after all I had made the initial contact, but it just sounded so unlikely that a computer security system of such renown would make that kind of error and not be able to fix it remotely. Frightened that I was letting a hacker in, I refused to hand over control.
That has left me, rightly or wrongly, wondering if there is something seriously amiss with my account. Is there any way I can get reassurance that I am dealing with genuine Avast staff? I would like to stay with Avast, but having a question mark over security is almost like having no security at all.