Gutters overflowing into Qld Room

I have a Queensland room built on the back of my brick house. When it rains heavily the water pours over the gutters and floods the room. The roof is set higher than the gutters which are the originals from when the house was built . Does anyone know a way to solve this? I was thinking that I could put sheets of roofing all the way to the edge of the tiles and cover the gutter this way so that the water went directly onto the Qld room roof but dont know if it will work. Please help as I want to tile it but don't want to waste my money if it is going to be ruined by the rain. Thanks

Having trouble getting my mind around exactly the setup. can you post a sketch ??

HI
Thank you for your interest . I have attached a photo.
Cheers
Natalie

I don't think the problem is with your gutters overflowing. Those are big gutters so should handle the rain, unless there is a blockage in your downpipe.

It is more likely to be a sealing problem. A flashing at the top edge of the Qld roof would stop the water coming in. A closer investigation is required.

Hi
Thanks for looking. I think there are a multitude of problems there. The gutter has a 90o bend at the end as shown in the pic then 4m later they have another one at the end of the house so it goes along like a backward z so I think that is one problem. Our house has a lot of water problems which we have hopefully fixed a lot of them. We had big roots thru our pipe when we bought it so we dug them all out and put in 100mm pipes to take a bit more water as there is only one storm water pipe running to the gutter to handle all the water off the right side of a fairly big house. I have taken the downpipe at the front out of the system to relieve the load and put a pipe on it so the water runs onto our front lawn instead so there is only one down pipe in the stormwater pipe. Our water struggles to get away due to our street gutters being crap. We have a very long block with no drop boxes at all along it and a 300mm pipe at the end to handle all the water that comes down! We put a 90o stormwater connection onto the end of our pipe where it goes into the gutter when it rains and this seems to help as our water just joins in the rush instead of not being able ot get out at all. We get water from our neighbours up the back when we get decent rain so we have put in cement with grates up there. We have been flooded twice to the degree that the fire brigade had to pump us out. Thankfully the first time the water only got inside a little thru the seep holes in the bricks and the second time none got inside it was only lapping at the glass sliding doors in the Qld room.
I have put silicon in the little slits in the guttering in the Qld room to stop the overflow and tried to seal the top edge as well to no avail. I worry about doing this as I dont know if the water will overflow in the back of the gutter and go inside the house???

How would i put flashing there? I was going to buy this metal strip at bunnings once which slipped on the edge of tin and had a bulging curved bit on the front to see if that helped and there was another one that was just straight but had been bent into a 90o half square that I imagined would stop something. I am at a loss as I don't know much about any of this and my hubby knows about the same. Any help or suggestions would be gratefully recieved.
Cheers
Natalie

If anyone could help me out i would greatly appreciate it!!!!