Equity LifeStyle Properties review: Failure to refund money owed

After 28 years as a tenant in The Highlands at Brentwood (HAB), a 55+ community in Mesa, AZ belonging to ELS Properties, my mother Shirley Leppink (age 93) sold her mobile home there due to health reasons. I am her son and have POA to assist with her affairs. All notification to HAB pertaining to a sale were made (verbal 5/19; written 5/25), they approved our buyer on 6/12/2023, confirmed it on 6/13/2023 and the sale completed on 6/14/2023. Because we paid the required full month of June rent at the beginning of the month, we are due a pro-rated refund of $519.33 for the 2nd half of the month. The primary applicable laws are AZ Mobile Home Parks Residential Landlord and Tenant Act 33-1413E (pro-rate) and 33-1452F (sale). I request the $519.33 refund or binding arbitration to resolve this dispute. I have evidence for all my statements and have shared it with HAB/ELS Properties.

The responses ("justification") from ELS have been without legal merit and nonsensical. They refer to untruths and irrelevant or misunderstood sections of AZ law.