How long have you been roaming may I ask @Ibrahimmerie as the service is for short term only with Vodafone now clamping down on what's classed as long term roaming.
More in Global-roaming and Is there a limit on how long I can roam for ?
That said as a process of elimination try your sim card in another phone and or choose a different network.
Sometimes masts are at issue too so is this happening in one place or everywhere ?
Current Phone >
Samsung Galaxy s²³ Ultra 512gb Phantom Black.
