Phone calls at unreasonable hours

On the 24 September I've received a phone call at 8 in the morning, on a public holiday, or 7 o'clock on the 25, then I'm still on my way to work. It's very annoying. I have never ever missed one payment. Our arrangement is the 25th of the month. I didn't had any access yesterday but paid them first thing this morning, I've already received a call and a sms. You make us feel like \*****s". When I made arrangements I was never told that you will charge high interest fees"