Line off for 31 days, no help from BT, what to do ...

Question

My company's phone line has been off for for 31 days. We now have been able to have calls divered to our credit card terminal's line, but that's obviously intefering with our ability to process cards. Now we can't make or receive calls when cards are being processed and can't process cards when we are making or receiving calls.
Phone orders aren't as important for us as they would be for many other businesses but we are still a couple of thousand down compared to last August, and this certainly has helped.
I've phoned BT Repairs so many times, waiting up to thirty minutes to get through to someone, and each time been promised my phone line would be fixed that day, only for nothing at all to happen.
I'm sure if we were a new customer we could have had a new line connected in a flash but BT clearly places far less value on their long time customers. I presume you think because we've remained with you for over 20 years I'm willing to put up with anything and will never leave.
What is there that I can do to actually get my phone number back online? Who can I contact?

Answer 1

I am looking for information about who you go to when you've exhausted all options with BT Business (or indeed any part of BT) and need to escalate it to the very top which presumably would be the same people residential customers in my situation would have to contact.
I doubt I will get much help on the BT business forum which from the look of it seems to attract only a handful of posters a month, most of them in similar situations to me who get no response from other users let alone any BT employees.
If it helps you can imagine that I’m a residential customer who’s had no phone for a month, phoned BT Faults every couple of days and after 30 minutes of queuing each time been promised my phone would be back on later that day and every day nothing at all happens. Then imagine that nobody at customer service will return calls or do a thing for me and I look no closer to getting my phone back on today than I did a month ago. Who do I now contact?