no need to visit dealership workshop - its a pretty simple job. Its best to do other maintenance while at it. You need to buy these parts.
Timing belt (genuine suzuki or genuine Gates, mitsubishi etc)
T belt roller tensioner
oil seal for crankshaft snout
oil seal for camshaft
water pump (its right there and is old as heck too - unless you changed it recently)
The oil seals would be cooked hard at this age, replace them to prevent future agony. word of advice, If the mechanic is resorting to lever off the crank pulley with a screwdriver stop him - he might break the crank sensor trigger wheel, Instead get a crankshaft damper puller and do it properly. A good mechanic should have it though.