Indesit Hotpoint Dishwasher Repair Failure

I accidentally registered a service request for my Indesit dishwasher as Ariston service through Servisfoni. I canceled the entry an hour later. After that, I called the official Ariston service to let them know about the problem. They said they would come sometime between 3:00 PM and 5:00 PM, but two people showed up at 2:40 PM.

I think they were from Ariston service because I had canceled Servisfoni, and even though I asked multiple times, they confirmed that they were the authorized service. They sent a bill for 2100 Turkish lira and asked for a payment of 500 Turkish lira in advance. They said they would put in the part tomorrow. I didn't realize I forgot to cancel the appointment with Servisfoni until the authorized Ariston service actually showed up. When I called, they told me to call a different number.

While I was on the phone, I got some inappropriate replies. They said they wouldn't give back the 500 Turkish lira. I'm not sure if the part they're going to install is accurate because they haven't been honest, so I want a refund for the money I paid.