Claiming compensation from developer for delay in handover

I have purchased a property off-plan, which was due to complete Sept 2020, however, the project has been delayed and not even reached 10% completion.

And now with the COVID-19 situation, the developer has decided to prioritize other projects and informed me the unit I purchased will be delayed as a minimum for 2 years.

But to make good by me, they are offering me a unit in the sister development for the same price, which is one of the projects they are prioritizing to complete.

But they are only offering it to me at the same square foot price as the other unit, and this unit is slightly smaller too.

Also, this project is anticipated to complete q3 2021, which is 18 months later than what signed up for with the first unit.

I want to understand what compensation I can claim as I feel they are not offering to be adequate compensation for the delay and nor doing be a deal on this unit.

Please advise. Just to highlight the delays to the first project were before this COVID-19 issue.