Computer Mania review: exchange?money back

0n the 18/12/2013 my husband bought a Mecer tablet S10 for me for Christmas.
The 25/12 I started switched it on and the 26/12 after charging the unit it just did not want to go to the basic menu and kept on insisting on only emergency calls, which this unit did not even dial.
At the soonest we could I send this unit back to the original store where we bought it
Cape gate shopping centrum, the young man said that it is a software problem, they did not have any in stock to exchange as I was in exchange policy from the store time frame.
They then told me to go to Paarl 35km from them and exchange the unit there, what i also picked up that on this slip from Paarl there was no additional information of any exchange policy as if it was deleted from slip/system
Because it was weekend he could not get any one from H/O
I then asked for something the same for which I can exchange .Nothing
I ask then for a refund .Nothing.they flat down refused.
We went to Paarl and exchanged unit
When we got home the battery needed to be charged we did that
When I started the unit on the 29/12/2013 I could see it was used before and not a new unit as the email address is under werners self med the back ground the time being already on unit

Now my problem is as follows
1. We spend R3499 in that store
2. The unit had a problem according to them one with the android
3. They had no stock to exchange
4. They could not extend the exchange policy to the next week for me to get a new one
5. According to the consumer law I can have a refund if I am not satisfied with product
6. I had to use my petrol and time to go and fetch this second hand unit
7. I called the store to ask the managers surname Andrew answered phone first he put the phone in my ear down then when I called again he said the manager just said to say Grant from Cape gate
8. I am very unhappy about the way they handled the problem and I still have a second hand unit
9. Ian who sold the unit to my husband opened the box before my husband left store . when the unit was taken back it was said that they cannot refund because it is not in its being opend. How on earth would we know it is faulty if you don’t start it?
10. There is no after service to satisfaction

I am awaiting reply from you to solve my problem as soon as possible
I only want a brand new unit or my money back
And I do not think that is too much to ask as I have spent a lot of money in store.