Looking after a friends pet

In a couple of weeks one of my best friends is due to go away on holiday to Canada and she has worryingly asked me to look after her 2 new guinea pigs for her whilst she is away. It’s not that I don’t want to look after them for her it’s just that I don’t have a very good track record when it comes to looking after friends/neighbours pets’ whist they are away. A couple of years ago a neighbour asked me to look after her cat when she was in Spain. It was all going well until one night when I came to feed the cat it didn’t turn up, it had a cat flap so it could come and go as it pleased but for the past 5 nights it had always been back in the house when it came to feeding. So I left the food in her bowl and figured she would eat it over night, but when I checked the next morning the food has not been touched and there was a note through my neighbours door saying ‘I’m sorry but I ran over your cat, please call me’. Turns out someone has run over and killed the cat and I had to break the news to my neighbours when they came back from their holiday!