Unusual heat issue

I'm new to this forum so sorry to come straight in with a question but my 06 octavia 1.9tdi 140 elegance is blowing fine temp on the drivers side but cold only on passenger side irrelevant to what the dial is set too. I only have this car a week and it's a taxi so even though i've covered alot of miles in the past week it has not rectified itself like others I've heard of. Has anyone any idea?