VolKano headphones too loud and cannot lower it

I received a volKano wireless Bluetooth headphones for my birthday as a gift.my wife bought this from Makro just before the lockdown.It was kept unused until a month ago when the office told us to join meetings online.The headphone look great and connected to well but the lowest volume on it is just too loud and hurts my eardrums.I tried calling Makro for assistance and went on VolKano website to look for ways to drop the volume lower but it’s not possible.My wife wants to return the item but we lost our receipt and don’t know what to do.Can someone from Makro advise on what to do for a refund voucher so we can buy a better model that has lower volume control than this headphones.Pls assist as product is not usable at moment and sitting in box unused.