Price Watch/You spot the prices, we ask the questions:This summer Mary Dunne completed a money transfer using Western Union at the GPO in Dublin for the first time.

"I wanted to transfer €150 to New York," she writes. "They told me that the [transaction] fee was €20," a sum she believes to be fair. However, when the transaction was completed, she saw that her €150 had become just $170.37. "I was shocked," she says. She had expected her €150 to convert into about $180. "I accept having to pay the €20 fee for the service but I find it difficult to swallow having to pay another $10 because of an unfair exchange rate."

When she queried the rate with the person at the GPO "she informed me that the Western Union always had an unfavourable rate when compared to other institutions". And that is the case. Earlier this week the Western Union's Irish website said PriceWatch's €150 would become just $173 when sent to the US via Western Union.

According to this week's rates, €150 should be closer to $184. On the Western Union site, the company accepts that its "exchange rate may be less favourable than some publicly reported commercial exchange rates used in transactions between banks and other financial institutions".

It says it uses an exchange rate which is "comparable to rates used by bureaux de change and other retail currency exchange facilities which offer exchange of comparable amounts of currency to the general public. Any difference between the currency exchange rate offered to customers and the currency exchange rate received by Western Union will be kept by Western Union (and, in some instances, its agents) in addition to the transfer charges."

To compare Western Union rates with other rates, we contacted a bureau de change in Dublin city centre and were told that for €150, we could buy $176. The bureau de change said it charged 2.5 per cent commission on the €150 and offered a rate of $1.202 to the euro.

According to the Western Union website, the best it could offer earlier this week was a rate of $1.15 to the euro. The rate being quoted on international markets earlier this week, meanwhile, was $1.228 to the euro. Another reader has had a problem with exchange rates, although it is much closer to home. Chris Flynn recently bought a box of Nice & Easy hair colour in a chemist in Newry and paid £4.27 (€6.34) for it. The same hair colour retails in Dublin for closer to €8, she says. While in the Newry chemist, Flynn's mother also bought Recital hair colour, and it cost £4.73 (€7).

"The same colour in Dublin retails for about €10.25," she says. "Both prices appear to be double the sterling price. Is this another case of the sterling price not converting properly to euro?"