Business ProfileforGopher Patrol

I have used Gopher Patrol on and off for a number of years - depending on gopher activity. I called them on 6/11 and it was explained to me that due to changes in their billing, they say they have changed their address for billing which has resulted in 4-6 week delays in processing payments. Due to issues with billing I cancelled my service and requested the outstanding balance - reported as 123.20. I mailed that amount on 6/11. On 6/18 I received a notice from a reported collection agency for the amount of 123.20 (ARM Solutions Inc. PO Box **** ********* CA *****-****). Called Gopher patrol whose voicemail reported that they only take calls M-F. 6/20 called Gopher Patrol who apologized for the error and would have their billing department call me in 24 hours. 6/21 - no return call. I logged in to their customer portal and paid with a credit card the outstanding balance of 123.20. Checking later that day they also cashed my check for 123.20. Called ARM on 6/22 and a message says this is a bill collector and hangs up. Tried the number twice with the same result. 7/5 received another letter from ARM, more threatening than the last. 7/6 Sent a written response to the ARM letter using their provided envelope stating to stop the harassment and refund my balance of 123.20. Please note the ARM form simply goes to the Gopher Patrol address in Corona. I have legal services with my work, and I will be reviewing monetary remediation beyond the amount they owe me of 123.20. The cancelled check and credit card receipt can be provided if needed, as well as the top portion of the threats sent by ARM.