Poor Service

I bought items online and opted to collect from their pick up point and when I went to collect the items discovered that they were not the ones I ordered and immediately logged an exchange and was told that I must take the wrong items with me and return after getting an sms. Why must I take the wrong items with me and who will bear my traveling costs. Please resolve this ASAP and refund me my costs for travelling. A single return trip is about 60km.