Which LDZ / Local Distribution Zone you are in has a significant effect on your gas bill. This applies to both the standing charges and the unit rates or price per therm. Unfortunately, it’s also something you can’t change, short of moving your business. Your LDZ also dictates who you will need to contact to upgrade or downgrade your supply or if you are looking for a new supply.
The WS area covers the following area.

Towns
Aberdare |
Abergavenny |
Abertillery |
Ammanford |
Bargoed |
Barry |
Blackwood |
Brecon |
Bridgend |
Burry Port |
Caerphilly |
Caldicot |
Cardiff |
Cardigan |
Carmarthen |
Chepstow |
Clynderwen |
Cowbridge |
Crickhowell |
Cwmbran |
Ebbw Vale |
Ferndale |
Ferryside |
Fishguard |
Goodwick |
Haverfordwest |
Hengoed |
Hereford |
Kilgetty |
Lampeter |
Llandeilo |
Llandovery |
Llandysul |
Llanelli |
Llanfyrnach |
Llantwit Major |
Llanybydder |
Maesteg |
Merthyr Tydfil |
Milford Haven |
Monmouth |
Mountain Ash |
Narberth |
Neath |
New Quay |
New Tredegar |
Newcastle Emlyn |
Newport |
Newport |
Pembroke |
Pembroke Dock |
Penarth |
Pentre |
Pontyclun |
Pontypool |
Pontypridd |
Port Talbot |
Porth |
Porthcawl |
Saundersfoot |
Swansea |
Swansea |
Tenby |
Tonypandy |
Tredegar |
Treharris |
Treorchy |
Usk |
Whitland |
Counties
Ceredigion |
Swansea |
Pembrokeshire |
Glamorgan |
Monmouthshire |
Carmarthenshire |
The WS Distribution Zone is operated by Wales and West Utilities