Bad internet speed and no response

I had Telkom LTE installed last year September. <br> Before signing up, Telkom sent someone to my place to run a tes.<br> It was very promising, download at 40Mb and upload at 20Mb.<br> After about a week , the speed started to drop , and finally went down to 2Mb download and 0.1Mb upload.<br> It took Telkom some time to send someone to check the problem and then waited more time for them to install the booster.<br> After the booster installed, the speed went up to 14Mb download and 4Mb upload.<br> But after about a week, the problem started again, and this time the download speed is only spiking between 16mb - 6mb