Babysitting,£15 but the mum wont come home

ok so im looking after 3 kids on saturday for £15 is thatlow or what but I suppose she is kinda struggling but she only 23,my mum and family are insisting I say no as she comes home 3-4 days later..but I dont mind she lives like on the same road as me...

but right down the bottom,and its a bad place at night the kids are aged 1and a half... 6 and 8.

It's not about not minding. How would you feel if you were left alone for days at a time without your parents? She's being an irresponsible parent, and either social services needs to get involved, or she needs to get her act into gear. You cannot raise these children, what happens when you're no longer around? You need to think about these kids...