Selling right to buy property. Dispute over % discount I need to pat back.

[Preggy]

I purchased my house through RTB, ownership started on 18/06/2017.

I want to sell as we need a bigger place. I worked out the following based on when I took ownership of the property...


18/06/2017 to 18/06/2018 is Year 1 of ownership
19/06/2018 to 18/06/2019 is year 2 of ownership
19/06/2019 to 18/06/2020 is year 3 of ownership
19/06/2020 to 18/06/2021 is year 4 of ownership

Which should mean from 19/06/2020 I am into my 4th year of ownership, so I have to pay back 40% of the discount. As per the official government guidance found here: https://www.gov.uk/right-to-buy-buyi...ling-your-home

However the housing association have come back to me and said the following....
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I had to go into a meeting yesterday, sorry. Please find the below:-

• 80% of the discount in the second year 18.6.19 – 18.6.20
• 60% of the discount in the third year 18.6.21 – 18.6.22
• 40% of the discount in the fourth year 18.6.23 – 18.6.24
• 20% of the discount in the fifth year 18.6.25 – 18.6.26

So if you wanted to sell in June this year you will have to pay back 60%.
The amount you pay back depends on the value of your home when you sell it.
Hopefully, this gives you an easier understanding.
Regards,
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I am almost 100% sure this is incorrect what they are saying. For one the dates are all over the place. Can anybody tell me who I need to go to get this cleared up?

Lee