The handover is delayed and the size of the property is changed. What to do?

I have purchased a property that was due by the end of 2018.

A few days ago I have received a notification that the property is ready for handover, however, during the "snagging" I could see that the building will take at least few more months to reach completion!

Mashrooi states 92% completion only. I asked the developer for compensation for the delay - according to the contract, it should be 1% per quarter which should be 11-12% by now (3 years), however, he is saying he will do a maximum of 7%.

In addition, the drawing of the unit in my contract differs from the actual studio. The outline is different and the size of the unit is 35 sq. m. vs. 50 sq. m as shown on the drawing.

The developer points to another page where the 50 sq. m is stated as a gross area rather than a net area. However, if placed directly under the drawing of the studio, shouldn't this refer to the net area?

With the difference in size as well as the 3 year+ delay, do I have a chance to ask for a refund of my 50% investment?