Keep getting barred?

[Hornet]

I switched from £10 rolling to £20/month contract, but I keep getting a message saying 'insufficient credit' unable to text, make calls, access internet.

VM keep clearing this by adding credits to my contratc, but I alreaqdy have credits when they do this. They are unable to explain why every two weeks my phone gets barred!

Any ideas what going on?

I have never defaulted on a payment so no idea.

Thanks

[Hornet]

Three consecutive days of not being able to use my phone VM have no idea why it is happening!!! Great service. Their tech team investigation...promised to call me Friday....no one called!