Nutella App Blocked Me from Completing the Campaign and Earning My Reward

There are 29 tasks in the Nutella app's Ramadan calendar campaign. I have successfully completed the tasks so far, but I am having problems with today's 'invite a friend' task. There was this task before and my friends became members because I shared my reference code in my WhatsApp friend group. Now there are people who want to become a member with my referral code, but since I have completed my 3 friend invitations per month, I can't do this 15th task and I can't get my reward. I talked to customer service and they said that the terms of participation were shared on social media, but I didn't see anything like that. It could have been stated that there would be friend invitations in the tasks and it could have been recommended to use the three rights from time to time. Since I signed up with my reference code, I filled my three rights and was eliminated from the 15th task. The first 15 tasks were supposed to be rewarded, but they are doing their best not to give the reward. They said they would accept it when I do my task the next day, but I will be eliminated from the grand prize because I will not be able to complete 29 tasks. Also, I will not get the prize given to the first 300 because I am too far behind. I think it is unfair. I invited 3 friends to the Nutella application and they downloaded and installed it. Nutella is making an effort not to give me the prize I deserve.