The problem they have is - all matters involving real estate and contracts which are longer than 1 year have to be in writing?
Did the apartment complex state in writing that they would make the aparment handicapped compliant?
Then your parents are going to have trouble - their arguments are violative of the "Statute of Frauds". The Statute of Frauds mandates that contracts involving land and that last for over 1 year must be in writing.
Certainly they can make their arguments - that the apartment complex verbally agreed to make the modifications - but it's going to depend upon the Judge if he will allow the oral agreements into evidence. If the Judge does allow the evidence of the oral agreements into evidence - then your parents should and will win.
The ADA only applies to "NEW" construction or remodeling of existing structures - as this apartment complex is already in existence and use - the ADA does not apply to them.
I'm not real sure what your asking in that question.
If they break the lease - they are liable for the lease terms (the monthly payment for the full term of the lease) and potentially court costs and attorney's fees.
The apartment complex has a duty to mitigate the damages - find someone else to rent the apartment - however, when dealing with large apartment complexes with multiple units for rent, the aparment complex usually shows an apartment in your parents situation last and therefore your parents are usually stuck with paying pursuant to the lease agreement.
Lawyer
19 years extensive experience in real estate law, foreclosure, finance, and landlord tenant law.