student loans overpayment

i was studying last year and dropped out due to my mental health. i dropped out in june after trying to beg my uni for mental health support for months and being added to the bottom of a waiting list. i was still trying to be a student but i couldn’t even bring myself to go outside. when i dropped out my uni changed my date on my withdrawal form to the start of april and reported this to student finance. student finance now believe i was overpaid my loan last year and are demanding i repay them almost 5k which obviously i don’t have. that half of my loan went on my rent. i’m now at a different uni after working very hard all summer to mentally be able to be a student but these constant calls and threats of collection from the student loans company are destroying me again and when i try to explain to them that i’m still a student and don’t have the money they just do not listen to me. does anyone know what i can do? i have proof of asking my old uni for support through emails that i’ve forwarded to myself but i don’t know if anyone will even listen to me. i don’t have any family or friends so no one can help me. honestly just reassurance that it will be ok would be appreciated. has anyone been in a similar situation before? what did you do? what’s even the least you can pay them back if you do set up a payment plan? like i said im at a different uni now and i’m completely on my own so i’m not exactly in a position to save anything let alone almost £5000. i don’t even know where to start but i can’t keep living with this fear over my head.