Ban companies from charging single people higher prices for holidays

Single persons who wants to go on holiday to have a break will see good deals advertised per person. However, it has been my experience that as soon as you put that you are travelling alone you have to pay for a second person too to get that deal or face a higher price if only paying for one person. I think this is very wrong and I think it's discriminating for single people and the companies shouldn't be allowed to do it.