I think the oil shop owner ripped you off!!!
You can always buy Caltex oil from their authorized pumps, no fakes there... Avoid these open market oil shop wala at all costs. Always purchase oil from authorized dealers.
Yes you can get oil change done from anywhere you like...
By the way Zic was a better choice. Go for Zic XQ if you are looking for better results, and drain it after 8-10K kms.