I purchased gold jewellery weighing $8$ grams from a jeweller. He offered to reduce GST on the jewel if I did not insist on a bill and that I should pay in cash. I agreed. After one year, when I wanted to sell the jewel, at that time. I found that the jewel was not made of $22-$Carat gold.

Which of the following conclusions are correct?

I. I have no proof of purchase; hence I may not get my grievance addressed.

II. My statement that I purchased the jewel from a particular seller is enough to get my grievance addressed in a consumer court.

III. I should not have avoided payment of GST and I should have insisted on getting a bill.

IV. I have facilitated the jeweller to indulge in a series of tax avoidance such as non-payment of input tax and income tax.