Contract Law: Contract Law

I kept my car in a garage which I rented from Ian at a rental of $100 per month. My car was involved in an accident and was off the road for repairs for a period of six months. During that time I had no need for the garage. Feeling sorry for me, Ian told me that I need only pay half the usual rental for that period. I gratefully accepted. After 2 months Ian had second thoughts and asked me to pay the full amount. In the meantime, I had spent the money on a bicycle to enable me to get to work.

Please advise whether I has to pay the full amount of rental?

Contract Law: Contract Law