Poor WiFi - slow or non existent in parts of house

[TOH]

I have paid for extra house coverage. The WiFi has been consistently slow, or non-existent across parts of the house. The test run on the app says WiFi is good except to one item, which is in the garage (that is part of the house). Why is the WiFi not reaching the whole house with consistent speed. The TV in the living room is constantly glitching out with the wheel of doom on bbc iplayer, Disney and prime. 

[TimmyBGood]

@TOH 

Sky loans wireless booster hardware 'free' under the terms of the 'WiFi Guarantee' element of the legacy 'Broadband Boost' add-on and the 'Enhanced Wall to Wall WiFi Guarantee' part of the 'WiFi Max' subscription supplement: they don't otherwise provide or sell boosters except to resolve issues with Sky Q. Phoning Sky to go through a telephone diagnosis is required to have a booster or pod allocated to the account. Inevitably some  Sky booster hardware has leaked onto a certain auction site and elsewhere online but Sky won't offer support with using these, and Max pods acquired that way won't work at all. 

Confusingly the default 'Wall to Wall WiFi Guarantee' bundled with all new Sky Broadband orders where Boost or Max is not added by the customer doesn't actually provide booster hardware, and is essentially a sales lead generator for the supplements mentioned above plus a one month broadband subscription refund.