Number blocked unfairly

I have a contract with Intellicell, which I have been paying well. I chose the 1st of every month because that is the day we get paid. For them they decided on the last day of the month which I didn't see a problem. The problem now is that they expected the money on Friday the 28th June which It's not what we agreed on and the was no money on my account so on Saturday 29 June they blocked my number.

Remember I didn't skip a month"s payment it's just the day they assumed the money will be in while I'll be paid on the 1st July which is Monday. This is even before the last day of the month. I took a contract with my main number which for says I committed to these payments, if I had plans of not paying I would have taken their number. They can deduct the money on Monday the 1st of July it will be there.

We never had an agreement of the 28th.