I have paid £73,000 holiday lodge. Before buying it,

I have paid £73,000 for a holiday lodge. Before buying it, we had to work out that we could make a decent return. It would be required to make an income for our retirement. I asked about the costs relating to sub-letting from the sales person. She said that the company charged 20%. Using this figure, along with information about rates, electricity, depreciation and site fees I worked out that we could clear a possible £420 a month income, which would be acceptable to us. On the day of signing, on Saturday, I asked a further question about whether there were any other costs such as cleaning to take into consideration. The sales person replied that "yes, cleaning was additional, but I don't know exactly how much - you would need to ask Arron, who will be around on Monday". I estimated the costs of cleaning and decided that the figures would still work out ok. Because we wanted to complete at the weekend to take advantage of a large booking, we were told that we would need to waive the 5 day "cooling off" period. That didn't worry us at the time, because we were satisfied that the figures were accurate. Today, we met with Arron, who gave us the details of the subletting agreement. It showed that there would be a 15 to 20% agents fee for a third party to cover marketing and booking etc. We were totally shocked about this as it made a difference of £3000 per year, which would mean that the purchase would not be viable to us. If we had known this before purchasing, we would never have bought it! Arron told us that the subletting agreement could have been printed off for viewing at any point before we met with him, but we were not offered this at any point. I believe that this was mis sold - what can I do?