You don't have to convince them or even share your reasoning. Just say No.
“Parents, I've given this a lot of thought and me buying a flat for you is not in the budget.” Repeat as needed. Stop arguing, Stop fueling the fire. “We've talked about this and it's not happening.” “We've been over this.”
If they keep bringing it up, hang up the phone/get up from the table/walk out the door.
Sounds like a good plan
You don't have to convince them or even share your reasoning. Just say No.
“Parents, I've given this a lot of thought and me buying a flat for you is not in the budget.” Repeat as needed. Stop arguing, Stop fueling the fire. “We've talked about this and it's not happening.” “We've been over this.”
If they keep bringing it up, hang up the phone/get up from the table/walk out the door.
This is easy. No condom, no sex, no exceptions.