Midas Midrand refuse to exchange part I purchased

I purchased a Steering rack Friday 30/10/2015 for R3300.00 from Midas 31 Church street. they had to order the part. When I got home I only found out upon stripping the car that it was not the steering rack that broke but the clamp holding the rack. I took it back the following morning and they advised to come back Monday only to find out seeing that they purchased the part from a supplier they cannot refund it or exchange it for items to the same value. No one communicated that if they purchase it from a supplier it cannot be refunded upon purchasing the part, I could have rather made sure if that was the case before purchasing it. As per the owner of the store, he will not sit with a part that doesn't sell the receipt says ... No refunds or exchanges on goods correctly supp****, electrical parts, tools & accessories. No cash refunds after 7 days. they should also state that if they supply parts they do not have in stock as non refundable.