Disgusting service and holding a line hostage

We moved into a new house, where the old tenants had cancelled their fibre. We've been trying to sort out our fibre and keep getting pushed back by the fibre provider as the current provider, MWEB, refuses to release the line. They refuse to assist myself, Vumatel or Cool Ideas and say they will only release the line at the end of the month, despite the fact that I've moved in and they no longer have rights to my property. We've been treated to dropped calls, been hung up on and treated with immense disrespect. I am utterly shocked that they're holding our line hostage and refuse to help, even refusing to contact the old tenants.