Someone else's account active in my property, query not resolved for 20 days

What a terrible service. Metrofibre is keeping someone else's account - a tenant that used to live in my house active. I have been contacting them since the 15th of August and they have been escalating my query to their orders department and their key accounts manager every day when i contact them. I cannot activate my internet because they holding the line in my property into ransom. Their support team daily answer is exactly " Please note that i have escalated your query, the order department will be in contact with you"

Metrofibre release my line, you cannot keep someone else's account active into someone else's property!!!