Ebiz.com — refund not yet received

I have applied for my cancellation long time ago (1 oct 2018) and i have not yet received my amount back.. After posting query for about 10-15 times, they just reply that it will be refunded soon.. Also, now they are asking me to visit ebiz house and return back the cheque that i previously received.. (The amount was not refunded from the previous issued cheque because the bank account from which cheque was issued was closed).. Now, i don’t find a valid reason to return back the cheque, because #1 that cheque is not valid so i can’t use it anyway.. #2 company keeps the records for those to whom to return the money, so it should know whether the amount has been refunded or not..
I have shared all the proofs with the person who made me join ebiz regarding that i didn’t receive my amount.. Why so i need to return the cheque back. It is the only proof with me for which i have to receive my amount.
Kindly tell as to when will my amount be refunded.
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