Zara refuses to swop L jacket for XL

I bought a black (jacket size L) at Zara Tygervalley. Send jacket to brother - he lives 700km from me. He informed me to get it in a XL. He sent jacket back to me via a lift 2 days later. I immediately phoned Zara Tygervalley to keep XL aside - giving them Zara Article Number. No XL in stock, but told me Zara Waterfront (ZWF) had 5 XLs in stock. I phoned the ZWF branch to keep an XL aside for me. Just before I was on my way to ZWF, I phoned again to confirm they still have jacket for me. Now I was told they kept a L size for me not an XL size. I asked them to keep the XL, I was put on hold while Sales Assistant fetched XL size. But then I was told that this jacket does not come in an XL!!! A day later I phoned Tygervalley branch, explaining what had happened. They offered to phone the ZWF since they could still see system that ZWF has an XL in stock. ZWF branch phoned confirmed they are keeping the XL for me. When I arrived at ZWF store I was told I could not swop the jacket since it was 12 days over the 30 day exchange period. It says nothing about 30 day exchange policy on till slip. I explained whole story to Store Manager. He refused. Refused. Refused.