Beware - No grace period despite what Avis claim

My 19 day rental was due to start and end at 430pm. When I got to the rental at the start of the holiday I was a lirttle early at c 4pm and explained that I was a bit nervous about taking the car early as I wasnt sure Id be back for 4 as I was dependent on a ferry and that id be happy to delay my hire. I was comforted by the reception staff who stated that there was a grace period of c1Hour which i thought would be ok. Avis take a further $100 at the start as a deposit and I got back to Halifax at 4.34pm. I was told that there was no grace peiod and I lost my deposit and it was explained tthat even if i was a minute late i'd be charged a full extra day's rental. This was the only poor service I received in Canada in nearly 3 weeks and I post this as a further warning to not believe anything these large rental/hire car companies tell you