I am currently using Link3 Cheetah Plus Package (20Mbps) for 1290tk per month. But recently their service has been really poor and when I complained, they asked me to a speetest which shows speeds of around 15Mbps but when browsing it doesn't feel like it and to this they really can't help. So I want to switch my ISP to a more decent one but I don't want to pay more than what I'm already paying. Any suggestions?

By the way, I am using a Xiaomi Router 4C, informing this here in case the router is causing a bottleneck or something.