Bata India — Credit note is invalid

I ordered Women's blue sneakers shoes of size 4 from online bata store on 4 of august. I received my product and when I opened the box there's a pair of shoes of size 5 instead of size 4 which is very big for my foot.Also they didn't send me the fresh product, the condition of shoes is poor.So I returned them and they send me the credit note.But when I apply that credit note on my new order on website www.bata.in, they shows that the coupon is invalid.
Also I called the customer care number so many times but they are not picking up my call and I also mailed them so many times but they are not responding...I didn't expect this from your side..After that I go to different different bata showrooms but they said that the credit note is invalid.I didn't expect this from bata...Please resolve my problem otherwise I have to take some legal actions.
order ID[protected]