Britony 100 combi leak

Our boiler is a Britony 100 combi and has recently been repaired (new diverter valve as CH would not come on). Since then it has developed a leak, making a small puddle by the sink (dripping probably once every 20 secs) i think from the main water inlet, but I can't be sure (have not taken the front off yet). The pressure in the gauge has also dropped below the minimum operating pressure (0.7 bar), although it always was a bit low and hovered around the minimum pressure. However, the water still heats up when the taps are turned on, and the CH seems to be working OK, although the hot water is taking a bit longer to get hot. Would the leak be causing the drop in pressure? Would it be relatively easy to stop the leak if the pipe just needs tweaking a bit to tighten it up? I'm a bit wary of opening any valves or anything knowing as i do absolutely zilch about heating systems

any advice gratefully received

thanks
fi

The mains water isn't connected to the system pressure.
The diverter is connected to both, though so call the repairer back; he should have checked for leaks.
It's quite common that some connecting pipe will start to leak at the other end from the one you're working on because you're moving it.. That shouldn't make it a chargeable extra! Usually all they need is tightening.

But if it's the actual inlet tap (small square head you turn) leaking from the part which turns, that's just the (usual) poor quality taps combis use.
They very often stop dripping completely after a day ot two. If it doesn't, then it will need replacing, and that would be chargeable.

thanks for that swift reply! i will check if it's still leaking tonight and give it another day maybe, but if it hasn't corrected itself i'll have to get the engineer back.