Poor quality diamond and white gold rings - stones falling off

I bought a white gold diamond rings last year July. The cluster ring I have only worn it just a couple of times mainly when going out on weekends and only wear the band on a daily basis. In January one of the stones fell off the ring. Took it to the store I bought from Mall of Africa and they took it in for repairs. During that time I read a lot of reviews with same situation of falling stones. I collected the ring 2 weeks later, only wore it twice and another stone fell off last week. I have been calling the store and head office to no avail. Today I went to the store only to find the store closed not sure of the reason and for how long it will be closed. All I am asking for is to be contacted so I can bring the ring for repairs and tightening of all the stones to prevent them from falling further or if possible to be refunded.