Can a dent collecter threaten you with the police if you dont pay up?

i got stuff on credit and ended up selling the items due to debt then i couldnt afford to pay them the amount they were asking i askedfor it to be reduced but they wouldnt so had to stop paying i had a debt collecter come out today and said if i dnt pay such amount today they was poilce waiting around the corner to arrest me i didnt have the amount and neither can i get it so offered to pay ex amount per week which they refused, then said they would give me till friday to pay and if not i will get arreseted for fraud and deception is this true i felt so intimidated and scared and bullied i dont know what to do i konw ive done wrong and have offered to pay it back weekly its stressing me out could do with some advice thanks