Constant challenges after Cancellation.

I signed up with Rain in 2020 and had endless problem with connections. I then decided that I want to cancel my contract due to the connection costing me more money having to find an alternative connection. I cancelled my contract on 10th April 2021. I spoke to a consultant who told me I will only be billed for what I used. Needless to say, on 1 May 2021 the full amount was deducted and I am baffled by how a company can do that but want to promote good service. The service and connection is highly pathetic. I will never return to Rain, I'd rather make sure to get fibre than to deal with them again.