Still waiting on trust fund to be paid to me for more than 3 month's now its just excuse upon excuse

I have been dealing with this company since 2017 after my grandfather passed away and left me with a trust fund that builded for me.The agreement in the contract stated that there must be payments made to me at the age of 25 then 30 and then the last one to be paid at the age of 35 which will then be the last payment. Everything went well up untill now coming closer to the date of me receiving a large amount of money..for the past 3 months i have not revieved the agreed amount of money that we agreed upon to be paid weekly.some weeks i will recieve less than other weeks..I have been fighting with them for some time now wanting to know what is going on and why have i not received any payments and also why is the payments not in full.They were also supposed to pay out a the large amount of money as i have already turned 30 which still hasn't happened and waiting for. Everytime i contact them and query about it they have some kind of excuse.if its not the loadsgedding then it is they have a system failure or the bank account that im using is incorrect or that there needs to be a set amount of money in my account before they can do the payment.then i was told that it would take 7 to 14 days for the funds to be paid which still hasn't happened and now they say that it would be paid within the next 72hrs. Also when i contact them they start getting very rude and tell me to not get arrogant with them..Lately i seem to be having endless problems with the company and empty promises.i feel like they are stalling for time or something because why haven't they paid me the way my laid grandfather wanted it to be paid..