Something similar happened to me with twilio - years ago I had a number 'parked' with them, my card expired, they never notified me, account went into arrears, and they cancelled my number. I was quite a special number, a UK '0200' number they'd released somehow, which shouldn't have been released. When they then acquired sendgrid, to add insult to injury I eventually found out that I was blacklisted and had to go through various validation procedures in order to do business with them, which I declined to do.