MBD Harassment getting out of hand

If I could give 0 stars I would. I am being harassed day and night despite the fact that it isn't my account and that they needed to change the contact detail. They are rude, start phoning from before 7 in the morning until night, bombard me with sms's and when you request to change the contact detail, they just put the phone down and start calling me again. THIS HAS GOT TO STOP! Isn't there an Ombudsman of some sort to stop this harassment? I keep blocking the numbers as they phone, but it seems that they have millions of consultants all phoning from different numbers.