Disappointed in exchange policy

I bought facecloths on the 3 for 2 promo and 1 of then was incorrect so I went in to go and exchange the 1 today, the manager at the till told me I cannot exchange these because it's on promo and for me to change the 1 I need to bring all three of the items back so the exchange can apply.. I found this absurd because all she needed to do was just exchange the 1 I was bringing back even if I was paying in the difference, I fail to understand how a retail company as big as clicks can have such exchange policies in place? I mean the system can be overridden, I even had to give the Manager Kedibone resolutions to the problem explaining how she can authorize the transaction and the was no need for me to bring all those things back.. can u imagine if I had bought a hundred of these and I just needed 1 exchanged would I need to bring all hundred of then back just to exchange 1 item, clicks needs better ways to manage their systems and also advise customers on these exchange policies that are not relaxed! I am highly disappointed that in this day and age clicks is still using primitive methods of exchange. I called their customer care line and spoke to Muhammad who was also of no help, telling me they cannot overide the manager and I asked him then what is the purpose of a call centre if we can not find solutions with u.. I wasn't assisted in the store and I am met with yet another obstacle from the call office with Luke warm responses as if I am speaking to an outomated machine with no effort what so ever to try and assist me as I was in the store at the time of the call! Y do we have people at a call centre who will give us the same excuses that we got on store level? Call centre is where we go to get professional help and solutions when the latter was not offered at the store... I am very very disappointed at the lack of service in this clicks store and what happened to going the extra mile, these policies are never explained to us upon process of sale but always when they are met with a challenge of having to assist a client, they can't even think out the box I had to give Kedibone and even Muhammad on how to resolve this and I don't even work in clicks! I have been a great customer to clicks and I keep returning to this particular clicks and whenever I have an issue I met by brick walls in the form of your staff...