Covered Parking must be mentioned in registration agreement when you purchase a flat from builder?

Covered Parking must be mentioned in registration agreement when you purchase a flat from builder? What if it's not mentioned and builder gives you a letter stating along with say for example A 707 flat this person has one covered parking... Does this letter without stamp considered as legal? Also since builder while purchasing the flat said as with covered parking say example flat will cost me 77L and without parking It will cost me 75 and with open parking it will cost me 76L that means he's charging me for the same so it should be mentioned in agreement that this flat say A707 with one covered parking will be sold to the said person. But instead build is giving a letter without stamp with just a signature that mentions following: To, Mr. ABC, Subject: Parking Letter Date: 01/01/2020 Mr. ABC, has booked a flat A 707 in the project "project name" situated at XYZ, BRTS Road, Some Nagar, Ravet, PUNE - 411021. and this flat is allotted with one covered parking. As we cannot reissue this letter please keep copy of this letter for any future reference and communication. Yours Faithfully, **** I know RERA says that builder cannot sell parking. Here, builder is not ready to mention parking in agreement at the same time not agreeing to give stam on above letter so it will look more legal and issues warning that "we cannot reissue this letter please keep copy of this letter for any future reference and communication." So not taking any responsibility for the same? At-Least builder can mention that We'll give documentation and details to society once it is formed so you can get the parking allotment from society if and when required What are my options here? In future I dont want to have any headache related to this as parking is not mentioned in agreement as If I may have to sell the flat since parking is not mention as new buyer would get same or different or no parking at all in this case how can i convince him that this parking is alloted to me and once he brought the flat he can use it otherwise buyer wont buy a property which wont have parking or will ask the same for low value? What are my options here? The above letter given by builder is sufficient enough? It wont cause any issues or the above letter should have stamp from builder to make it more legit or covered parking must be mentioned in agreement ? Thanks in advanced.