huge windfall or missed chance?

I purchased Ethereum presale in the first minutes of the sale, and spent one Bitcoin. I received a wallet that was funded with 1,000 Ether. I never checked the rates at presale but I did today, for the first time, and realized that this is only half the amount of eth that I paid for.

I double checked the linked BTC address in the json file they sent me from the presale 7 years ago. The 1BTC transaction was split into two addresses and only one half was accounted for.

I wrote the organization about it. I don't know what the probability of getting the eth 7 years later is, But since it was a product presale, it was their responsibility to deliver if I'm not mistaken.

Did I screw myself over by not discovering this sooner? Has anyone heard of similar troubles with pre-sale wallets?