The infotainment screen died last week in my 2016 Model S AP1, and when I took it in for service in Palo Alto I told my service advisor that I wanted to upgrade to MCU2 since it was only a few hundred $$ more. He replied saying that he wasn't sure if my car was compatible, but he would find out and he would call me to let me know before they get started working on the car. I got a text and a message on the app yesterday letting me know my car was ready, and when I showed up to pick up my car I found out they replaced the MCU1 with another MCU1. My service advisor said I could either pay the invoice, take the car, and when MCU2 was available they would schedule another appointment and I would just pay the difference, or I could leave the car until they got the part, which would be mid to late August. I chose their first option but I told him I wanted it in writing and he agreed, he said he would email me the receipt with the notes stating that I would come back to get MCU2 and just pay $2,500 minus what I paid yesterday, and he would also let his supervisor know. It's been only one day since the agreement and I still haven't got a receipt in my email, should I be worried that they might go back on their word?
**Apologies for my English, I'm still learning