How do I get the credit amount posted to my account refunded to my checking account?

I have been a long time Comcast Customer.  As rates climbed, I have tried to adjust my service to meet my needs most cost-effectively.  My most recent experience has been very poor, and despite numerous calls and promises, my issue is still not resolved.   I requested to receive a comparable price to T-Mobile Home Internet which was $35/month with 5-Year Guarantee and a $120 sign up bonus.  Comcast's response was to offer me "NOW Internet" at $30/month.  I agreed and was sent a new gateway with my Xfinity service scheduled to be shut down a few days after my "NOW Internet" service was available for activation.  My new NOW gateway arrived DOA so I took my old Xfinity xFi gateway to return and my DOA NOW gateway to the Xfinity Store by Comcast at 4475 Roswell Road, Marietta, GA 30062.  The store was friendly and took my old Xfinity xFi gateway and the DOA Now Internet gateway and provided a replacement "NOW Internet" gateway.  I went home and activated the gateway and was back online. 

A few days later (May 28th) I received a notification that I was being charged $120.  I looked at the billing statement and had a partial credit but had $150 in one-time charges ($30 - early termination, and $120 - unreturned equipment).  These charges were automatically withdrawn from my checking account.  I requested that this be refunded and was promised it would be in 3-5 days over a 60-90 min combination of chat and voice.  After two weeks of not seeing the refund, I contacted Comcast again and was advised that I was no longer a customer.  After spending more than an hour, I finally got another agent and again was promised that it would be resolved in 3-5 days.  Again, after a week with no refund posted to my checking account I contacted Comcast and the agent said a $120 credit would be applied to my account would then be refunded to me 3-5 days later as the account was closed.  

So now here I am a week later and can now see $120 credit (not the $150 errant charge amount) showing on my deactivated old account and still have has any refund post to mu checking account.  In essence Comcast has took $150 of mine from my checking and has held it for a month.  Now I have a new customer number, and while my service is working, my billing issue is still not resolved.  I am about to spend another hour to try and get this fixed.

Feel free to call me to discuss.