Unknown charges

I cancelled my membership in store in December. 4 days before I left the country. I cancelled both internet and mobile. Of course I would not be using them outside of America. The team told me everything was paid off and I’d receive a refund for a small amount for the days I didn’t use. The mobile was told it was free on top of the internet. Fast forward to February and they are trying to take $38.50 from my account which I blocked. I contacted support online and they told me it was a mistake and the team didn’t cancel my mobile properly. They assured me it it would be sorted and the balance zeroed out. Then one month later in March - I get an attempted charge of $108!!! I contact support again and they tell me of course this is a mistake I haven’t lived there for 3 months. They tell me I will receive a message on my UK line when it’s sorted and it’s been raised to higher team because they can’t access my cancelled account. This is horrendous, I can’t even use this bank account because of Xfinity. Sort out my balance! Zero it in the app, my account is cancelled I paid all my bills over 3 months ago now. I will be raising with the lawyers at work who will submit with FCC and if not pursue further action. It doesn’t need to be said that I will never use Xfinity for any of my work trips again.