Unfortunately, it sounds like too much heat was applied to this logic board. When replacing the Touch IC, excess heat can cause some tiny components on the flip side of the board (where the Screen connectors are) to flow in the solder but because they are covered in epoxy, they tend to get sucked upwards and can have flaky connections.
The WiFi IC is right next to the Touch IC and it is underfilled. The excess heat can cause the solder balls to expand but are constrained by the under-fill - which can cause them to bridge (short) or blow out.
The first thing you should have done is gone back to the repair shop and have them try to sort it out rather that you buying all of these replacement parts. Whether or not the board is repairable is open for debate. Some of the issues sound easily fixable (camera, flicker) and some are more difficult (WiFi).
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=== Update (12/10/2018) ===
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Thank you for your prompt reply. So with the phone sitting in the Itunes cable icon mode (dfu), there is no targeted fix to solve this issue? is there something you can suggest me telling the phone shop to check? Any help would be much appreciated. Thank you
Unfortunately, it sounds like too much heat was applied to this logic board. When replacing the Touch IC, excess heat can cause some tiny components on the flip side of the board (where the Screen connectors are) to flow in the solder but because they are covered in epoxy, they tend to get sucked upwards and can have flaky connections.
The WiFi IC is right next to the Touch IC and it is underfilled. The excess heat can cause the solder balls to expand but are constrained by the under-fill - which can cause them to bridge (short) or blow out.
The first thing you should have done is gone back to the repair shop and have them try to sort it out rather that you buying all of these replacement parts. Whether or not the board is repairable is open for debate. Some of the issues sound easily fixable (camera, flicker) and some are more difficult (WiFi).