*********** staff and useless call centre

I've tried numerous times to get the correct process of changing a business landline into a new company name but nobody is able to answer. We've been using the account for 4 years. It's been 2 weeks and there is still no way forward. I tried going the DM route on Twitter but am being ignored. Our business account is still in the name of the company who leased the premises before me. I need to order business products but unable to because the account is not in my name. What do I need?