I've been trying to give money to an airline and a hotel. But hard as I try, they won't take it.

The airline has a seat available. The hotel has a vacant room. And they're mine for the simple exchange of frequent-flier and frequent-guest certificates. But not for cash.Makes perfect sense, doesn't it?

Let me explain.

Understand first that I'm not referring to some travel-editor-only courtesy. The Houston Chronicle pays for all my job-related expenses. This is for a vacation. The airline (Delta) and hotel chain (Hilton) involved have no idea that I work for a newspaper. I'm just a guy surfing the Internet and perusing advertisements and brochures for bargains. Just like you.

For some time the co-pilot and I had been contemplating a late-spring escape across the pond. And she cornered me the other day to remind me about a column I'd written urging readers to book trans-Atlantic flights and European lodgings early because of anticipated record tourism on that continent this summer.

"You do read your column, don't you?" she asked.

"We won't have a problem," I assured her. "We'll go before school is out; there won't be crowds. And with Eurail passes, we can fly into any available destination. We'll travel in style, too. I've earned upgrade certificates with Continental and Delta; we'll pay the cheapest fare, then upgrade to business class across the ocean. It'll be easy."

My smugness was short-lived.

I called Continental's reservations department and provided a choice of dates. "I'm flexible," I told the agent.

"Nothing is available," she replied.

I hung up and called Delta. "We're willing to fly into Frankfurt, Munich, Berlin, Zurich, Vienna, Paris - it doesn't really matter," I said.

"Nothing is available to any of those cities using upgrades," the agent said.

"Wait a minute," she continued. "Let me try one other possibility. I can route you from Houston to Cincinnati to Chicago to Brussels to Munich, combining our flights with Sabena, our code-share partner."

I weighed the inconvenience against the growing itch to unwind in a Munich beer garden. "OK," I said. "I'd like to purchase two economy tickets - the cheapest available - and use my system-wide upgrades."

"That's not allowable on this routing," the agent said. "But if you'll redeem 160,000 frequent-flier miles, two business-class seats are available for free."

"But that's almost all the miles I've accumulated; I'll become miles-broke," I told myself.

I tried pressing the agent with common sense: "Let me see if I've got this right - you can give me the seats for miles, but I can't pay for the same seats."

"It's a routing policy," she said.

The temptation of soaking in the sun aboard a steamer on Lake Constance was too strong. I emptied my miles account.

Then I accessed Hilton's Internet site.

The co-pilot had clipped an advertisement about the chain's sharply discounted weekend rates. Would they apply in Germany? Yes, I found a Hilton in Mainz that promoted the offer.

Alas, the Webmaster informed me that the rate wasn't available on my preferred dates.

I called Hilton's toll-free number. "That's right, we don't have any rooms at the discounted rate, but you can have the room free if you'll redeem 20,000 HHonors frequent-guest points per night," the agent informed me.

So I'm sitting here today commiserating with every reader who has corresponded to express annoyance and confusion with the policies of those who supply our flights and lodgings.

You may already be too late to use frequent-flier miles and/or frequent-guest points for a European vacation. So don't follow my example and procrastinate.