How many tonnes of blackcurrants are used to make Sisca Cassis? (it's
a brand of blackcurrant liquer)

It looks like this is a competition of some sort. I sent an email off
to the company, and I got this response

"First of all, thank you for your interest in our company and our product Sisca.
Unfortunately, we are not allowed to provide you with any answer as
long as the competition is not finished. You should know that Sisca is
not only sold in your country but also in some other countries in
Europe...
Good luck for the game !
Marketing Dpt. "

So, looks like this is a game, and whomever guesses the right amount wins. 
Nenna-GA