Rates and poor customer service

I always borrow a car from Friday to Sunday

Last week I asked for extension n returned it on Monday the charged me normal rate and took of 20% discount

Now I booked the car on Friday 18th I was supposed to return it the 20th today but I’m running late I called for extension the guy told me I must pay normal rate per day no discount but I do have discount and I always receive discount

I’m disappointed as I’m a weekly client