speedometer probs.

[rajjii]

hi,everyone new to this forum so will be really grateful for any advice...
regarding my wifes 1999 yaris {i litre],,well what happened last week while she was driving,all the dashboard lights suddenly went off...no indicators,heating control,electric windows.speedometer etc....
so i took it to a local back street garage who i know well....eventually,after checking the fuse box,one of the 10 amp fuse was faulty, but after inserting a new fuse,it immediately blew,tried 2 more times and again it blew....the guy then put in a 15amp fuse and that seemed to stabilise everything...
however,driving home,the speedometer and odemeter are now giving problems with the speedometer going haywire...and odemeter not registering anything..

one of my concern,is having a 15amp fuse where there should be a 10amp fuse cause any problems?

now what can be the problem with the speedometer? the garage told me it probably requires a "speedometer diffuser"
after reading other forums,i,m led to believe it could be 1 of 5 other problems..
grateful if any one give me help on this...
thanks