Electrics

hi everyone i have recently been having a load of electrical problems, 1st of all my alarm randomly goes off other things are my central locking opens and shuts on travelling, my dash sudenly says doors are open when they arent and most recently my speedometer goes when it feels like it and my fuel gauge goes up and down promptin the refuel beep which is very annoying when it is going every 2 secs when my speedo isnt goin my mileage stops, these are all givin me a real headache, can anyone advise????