Avis does NOT want your business

I tried to book a rental vehicle, on the Avis website, for a trip to George in October. I have an Avis customer number. I selected everything I need including additional damage waiver, but when I tried to pay it said that my session had expired - and that I should return to the home page. I tried this four times and then called the call centre. Suddenly the waiver was 3 times more than on the website!! One would think that Avis would want the business - obviously not!!