changes in my rats behaviour

[marmite_madness]

hi,
i have two female rats, from the same litter, and approx 8months old (2 months old when i bought them)

when i bought them from the pet shop, they hadnt really been handled too much, so when the woman got the out of the cage, she picked them up by the base of their tails (i wasnt happy about this and made a complaint)
when i got them home, i gave them 3 days to get used to their new house and then i picked them up, they were a bit nervous, but ok.

they have been generally still nervous, even though i get them out everyday, its becoming a real struggle. they cling on to the bars of their cage when i try to get them out. they run off from me and hide in their bed and have now started biting.

it has got 100 times worse since i went on holiday for a week and gave my mum strict instructions to handle them for one hour a day (which she did, with great struggle to get them out)

since iv been back from holiday (it was the the end of october) they have been biting me as soon as i touch them, they kind of scream when i pick them up, and they bite me and scratch my hands to bits.

pinky was the more scatty one of the two, and she used to urinate on me when i tried to pick her up, that soon stopped, but is now happening again.
as soon as my hand enters the cage, she runs off, urinating all over the cage.

i have no idea why this is happening, any ideas?