Bad investment

Urgently seeking some help. I have been investing with discovery invest for a period of ten years which was a ten year plan and my returns are less than what I have payed .when I sent a mail to the complaints they said to me it was the brokers fault and also covid .They said I can go to the ombudsmen if I am not satisfied. Need some help if it is a fault on my side I can just let it go . Is this the way the investment work. Need some advise