If you stick with your original provider you should not have a problem. I was (and still am) with O2 and never had a problem.
Sharing from experiences of dealing with debt
The greatness of a man is not in how much wealth he acquires, but in his integrity and his ability to affect those around him positively.
Bob Marley. http://kallis3.blogs.iva.co.uk
I was with three and changed to EE during my IVA with no problems, I was very shocked that my credit searched went okay. I was in year 4 of a 6 year IVA