Hi. Can anyone help. I took my 2005 Ducato 2.8TDI motorhome to get repaired. They said the battery needed changing. On driving it home I noticed the speedo was lagging by about 30kph (eg. doing 100, but showed as 70). All other dash instruments are working fine. Never had problems and was working perfectly before the battery was fitted. Neither they or an auto electrician can help. Any ideas what could have caused it, or how to fix it, or who could help. Please!