Double Billing and Want Refund

For 14 months, my husband and I had two accounts to the same service address and didn't know it. After my husband set up the account, I called to get IT support in setting up the service at our home address. Another account was created under my name, and little did we know they were both being billed.

We have both paid the respective internet bill for our accounts for 14 months and didn't know we were both paying for the same internet service. My husband cancelled his account 3 months ago and we have been trying to get a refund for 3 months now. I would love some actual assistance with this matter instead of getting the run around from store, passed from person to person on the customer service line and chat. Each time we spoke we were ensured a ticket would be created or was created (it wasn't always) and that we would be getting a refund or that this issue would be escalated and resolved within 48 hours but the tickets would close immediately after opening and we weren't even given information as to why. 

We are owed over$850 for being double billed and this billing mistake and customer service is not acceptable. Stop taking advantage of your customers.