Money Mensch: Act now to see if you're owed £100s

The regulator Ofcom believes up to £10m worth of unclaimed credit is available.

● Why might you have built up credit?

It may be that you were paying line rental or other costs in advance. So, having built up a credit, when you left there were a couple of months left over. Alternatively, if you signed up for a promotional deal, this is often paid via a credit - for example, 12 months for the price of nine. Normally you will pay the monthly fee, but have a credit on your account at the end of the period.

Or you may have even been told you would receive a credit to your account after complaining about something, but never actually received it.

● Why haven't they paid out?

Mobile and broadband providers should automatically refund any credit left over when you switch companies. In the past, few have done this, with the exception of some such as BT, Orange and the Post Office.

The rest retain these balances unless you call and ask. And even though many are changing their ways thanks to moves by Ofcom, this won't affect balances from past switches.

● How much could I get?

Since I launched this reclaim campaign a few weeks ago, I have already heard of a number of successes for over £100. For example, this comment is from my forum: "Did as instructed and to my amazement have £144 refund from TalkTalk - well impressed."

● How do I reclaim?

In most cases, just call up your old provider and ask it if you have any leftover credit on your account. This can go back six years in England and Wales, or five years in Scotland. Step by step guidance for each company is available at www.moneysavingexpert.com/billreclaim

● Get back old Tesco vouchers

Now this one hits all the 15m holders of Tesco's Clubcard loyalty scheme. In a nutshell, there is now a way to check if you have any unused vouchers from the last two years and get them reissued. But you need do it quickly.

● How does Tesco's loyalty scheme work?

Shop at Tesco and present your Clubcard and you earn two points per £1 spent. Then every quarter, these are sent out in the form of vouchers. So, 1,000 points is a £10 store voucher.

● How to get back old vouchers

The Tesco website has launched a Clubcard section which lets you view your points and vouchers online. Hidden away in there is an option to show all the vouchers you have had, and whether you have used them. If they are unused you can then access them online, or call to get them reissued. See www.moneysavingexpert.com/tescoreclaim

Yet do go quickly as vouchers only last two years, so the sooner you reclaim them, the further back you can stretch.

● Boost the value of your vouchers

Once you get the vouchers, whether new or reclaimed ones, don't automatically spend them in store as you can more than double their value if you know what you're doing.

The biggest multiple comes from using them on things in Tesco's Clubcard Rewards brochure, which is available online or in store.

Here, each £5 in-store voucher becomes worth £20 to spend on things such as days out, gifts, jewellery or magazine subscriptions.

Yet this is being devalued on 6 December, when £5 will only become £15. Do also note that the values are based on the list prices, so you may be able to buy them cheaper elsewhere. Check prices elsewhere first to ensure you are redeeming on the right things.

The other way to boost points is via Tesco's current in store Big Christmas Clubcard Exchange promotion. But note: this ends on Sunday. Here you can double voucher values in exchange for another type of voucher to spend on specific sectors in store such as toys, baby goods, clothing and wine.

Either way, in order to maximise your voucher value, act fast.