ASKING TO RETURN TDS AFTER E FILING

I was working some inspection audit for a firm and they agreed to pay me 200000/- for overall process. And without my knowledge they deducted 20000/- and reflected against my pan.

Now they are asking me to file the Income tax return and claim the TDS which is reflecting under my PAN and payback them refund amount.

This TDS was done at AY 2018-2019. 

What shall i do, Why am i responsible to payback them for which they did unknowingly.